1. Field of the Invention
The invention relates to a process for preparing arylvinyl halides and sulphonates and arylalkynes by reacting haloaromatics or aryl sulphonates with vinyl halides or sulphonates in the presence of a palladium catalyst and a base and, if appropriate, subsequent elimination.
2. Brief Description of the Prior Art
Arylalkynes have great industrial importance as fine chemicals, starting materials for polymers and intermediates for active compounds (cf. EP-A 571 326 and EP-A 1 219 173).
While process of preparing arylalkylenes are known, they are disadvantaged by drastic conditions for the preparation, low yield and other shortcomings, as discussed below. Arylalkynes can be prepared, for example, from aryl aldehydes by reaction with triphenylphosphine and C1 building blocks such as methylene chloride or tetrabromomethane in the presence of strong bases (Chem. Ber., 1982, 115, 828 ff.). They can also be prepared by the reaction of electron-rich aromatics under Friedel-Crafts conditions to form acetyl aromatics with subsequent halogenation and elimination of hydrogen halide (Chem. Ber. 1965, 98, 3554 ff.).
Disadvantages of these processes are the often drastic conditions and at best moderate yields.
Also known for the preparation of arylalkynes is the reaction of haloaromatics with trimethylsilylacetylene (Chem. Comm. 2002, 278), acetylene (JP-A 2001 294541), trialkyltinacetylene (Org. Lett. 2001, 3, 1869) or alkynyl Grignard compounds (J. Org. Chem., 1997, 62, 8957-8960) in the presence of palladium catalysts.
These processes are disadvantaged by, the restricted availability of the alkyne building blocks in industrially relevant quantities and/or the difficulty of handling them and/or the undesirably high content of heavy metals present.
Further, known is the preparation of arylalkynes from arylolefins by halogenation of the double bond and subsequent elimination. However, a disadvantage of this method is the need to carry out the preparation in at least three reaction steps.
There is therefore a need to develop a process which makes it possible to prepare arylalkynes or particularly suitable precursors thereof from haloaromatics or aryl sulphonates in an efficient way.